This invention relates generally to nozzle controls for spray head assemblies and more particularly to a nozzle control which employs a valve poppet member operated by a shaft positioned in a downstream flow channel of the poppet member so as to move the poppet member against fluid flow when turning on fluid flow.
U.S. Pat. No. 5,370,316 to Lancaster describes a spring-biased actuator lever arm of a spray head assembly having an actuator shaft which extends into a sealed spray-head compartment for sliding a cam to move a cam follower and thereby open a poppet valve positioned inside a water supply passageway against water flow. Although the spray head assembly described in U.S. Pat. No. 5,370,316 to Lancaster has many benefits and has proven to be quite effective, it also has some problems. In this regard, a poppet member of the poppet valve is constructed of a relatively resilient material having a durometer reading of around 89 (durometer hardness) whereas a follower shaft, or a valve shaft, which extends from the cam in the sealed spray-head compartment to the poppet member is of a relatively hard plastic, acetal, having a durometer reading of more than 100. The cam-follower shaft, or valve shaft, moves axially and is embedded in the poppet member. However, fluid pressure tries to keep a sealing face of the poppet member pressed against its seat, thereby resisting the axial motion of the valve shaft. When the poppet member is heated, by hot water, for example, its resiliency increases. It has been found, therefore, that the poppet member does not always immediately unseat with axial movement of the valve shaft. Usually, the poppet member eventually does separate from the valve seat but when it does, it does so suddenly, which is also detrimental. In this regard, this sudden and uncontrolled release of the poppet member from the valve seat makes it impossible for an operator to know exactly when the spray head assembly will squirt water. Also, the operator is prevented from controlling the amount of water sprayed. Thus, for example, if the operator merely wants to fill a glass, he may not be able to do this because the stream of spraying water will be too strong. Instead, he will splash water on himself and the surrounding area.
A related problem with the spray head assembly described in U.S. Pat. No. 5,370,316 to Lancaster is that such continual flexing of the poppet member weakens the poppet member and thereby reduces its life span.
Yet another related problem is that the nature of the cam linkage described for operating the spray head assembly in U.S. Pat. No. 5,370,316 to Lancaster only can cause so much movement of the valve shaft. Thus, in some spray head assemblies, where the poppet member has become too soft, operators have not been able to open the valves, or poppet members, at all. That is, the cam moves, the cam follower moves, the valve shaft moves, and the far end of the poppet member moves; however, the poppet itself flexes so that its sealing face remains seated at all time and the valve never opens.
Still another related problem with the spray head assembly of U.S. Pat. No. 5,370,316 to Lancaster is that, because of the above listed problems, the poppet member cannot be made to have a durometer reading of less than around 80. However, a poppet member with such a high durometer reading can sometimes not be adequately closed by lower water pressures. In this regard, water pressure is expected to help press the poppet member against the valve seat surface when the poppet member is in a closed position. So that the spray head assembly can be used with lower water pressures, which still sealingly close the poppet member against the valve seat, it is desirable to make the poppet member of a material having a greater resiliency. But because of the reasons listed above one cannot do this without reducing the life of the poppet member and reducing control exercised on flowing water.
Finally, yet another problem with the spray head assembly of U.S. Pat. No. 5,370,316 to Lancaster is that, during fabrication thereof, manufacturers sometimes over-insert the valve stem into the poppet member. In this regard, one fabrication step for this spray head assembly involves placing a water-supply pipe with the poppet member therein on a jig. The valve shaft is then inserted from above through a valve-seat portion, or passageway, into the poppet member. However, it is difficult for the manufacturer to "feel" when he has inserted the valve shaft into the poppet member a correct distance, thus, he sometimes over-inserts it.
It is an object of this invention to provide a spray head assembly of a type in which a poppet member is operated by a valve shaft extending from a spray-head compartment to the poppet member inside a downstream valve-seat passageway which provides a finely-controlled flow of liquid, which does not cause undue distortion of the poppet member thereby reducing its life, which provides positive control of a sealing face of the poppet member, which allows inexpensive and exact manufacture of the poppet member and the valve shaft, which allows use of a poppet member having greater resiliency, and which provides a centering of the valve shaft during operation of the poppet member.